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Thomas Han

December 27, 2019

How to Block Spam Calls to Your Business

Learn how to block unwanted calls to your business, and how spam blocking technology from Telzio works.

Spam calls to your business can include telemarketing calls, cold calls, and robocalls. These types of calls can be for the purposes of sales solicitation and much too often, attempts at fraud. Not only do unwanted calls interrupt work, but they can also lead to phone scams and financial damages. To combat these malicious and annoying phone calls, Telzio has extended its Spam Filter to all customers with their business phone service at no additional cost.

In this article, you’ll learn how to block unwanted calls to your business, and how the spam blocking technology works.

What are robocalls, and where do they come from?

Robocalls are phone calls that when answered, play a pre-recorded message. Robocalls can contain informational messages from political parties or charities, but are often scammers attempting to steal personal and financial information.

Using an auto dialer, robocallers can make hundreds of phone calls per minute.

Robocalls often come from fake numbers, or spoofed numbers, to deceive people into thinking it’s someone else calling. A spoofed number is when the caller ID is disguised as a different phone number, such as one from the local area code being called, also known as neighbor spoofing.

While number spoofing is technically legal in the US, it becomes illegal when it’s used with the intention of harm or fraud.

Why is number spoofing legal?

Number spoofing is actually useful and necessary for telephone carriers today. Carriers need to be able to set the caller ID of an outbound call independently of which carrier the call is terminated through, and currently there is no technology in place (even though stir/shaken is being rolled out to address this) to verify that the caller is authorized to use the caller ID set for the number.

Related: FAQs about Caller ID Names

Can a business block robocalls?

Robocalls are just one type of unwanted call that companies have to deal with on top of the increasing number of telemarketing calls that are made possible with auto-dialers and cold calling software.

As a consumer, you can add your cell phone number to the national do-not-call list. However, business-to-business calls are not covered by the registry.

Some desktop and mobile phones have a built-in setting to block phone numbers one-by-one, but number spoofing makes it difficult to stop robocalls because the phone number is always changing.

So, how do you stop telemarketers and scammers from calling your business?

The answer is to use a business phone service provider like Telzio that has a robocall blocking feature.

How to block spam calls to your business

Telzio offers a Spam Filter that screens incoming calls based on your preferences, and then blocks unwanted calls. Here’s how it works.

When a call comes in to your business, Telzio cross checks the caller’s phone number with the largest database of spam call analytics in the US to give it a spam score. The spam score is based on factors such as number of recent calls made, frequency of calls, what numbers are being called, etc. These factors are analyzed within a fraction of a second to produce a score, which indicates the likelihood of that call being spam.

From the Telzio Dashboard, you can set parameters for filtering out calls based on their spam score. For example, you can set the system to automatically reject all calls with a spam score over 90. You can also, for example, set all calls with a spam score over 50 to display a warning message on your caller ID display, giving you the choice to answer the call or not. You can customize the message to say “Spam Likely”, or some other text.

Spam filtering rules can be applied universally to all the phone numbers on an account, and for each phone number individually. For example, you may want to be more aggressive with filtering out spam calls from reaching your CEO, and be more flexible on your main line where you have an auto attendant that doubles as a robocall blocker.

What’s great about the spam score is that you can see the score for each individual call in your call logs. A blocked call will still show up in the log, along with details about its spam score and why it was blocked. This way, you can evaluate how your filtering rules are working out for you, and if they need to be adjusted. Related: How to Create an Auto Attendant in 5 Steps

Blocking phone numbers, area codes, and countries


In order to avoid certain calls from being caught in the spam filter, you can also whitelist phone numbers.

In the example below:

  • all inbound and outbound calls to/from the 800 number are blocked,
  • all inbound and outbound calls to/from the 888 number are allowed, and
  • all inbound calls from Nigeria (country code 234) are blocked.

Spam Call Blocking Feature - Blacklist

Final tips for stopping telemarketers from calling your business

The Spam Filter and blacklist are two solid ways of blocking unwanted calls to your business, particularly robocalls and known spam numbers. However, telemarketers who don’t use a robocalling software or spoofed numbers may still use manual efforts to get through to your employees through traditional cold calling. Here are two more tips on how to avoid telemarketers.

Use an automated attendant

Auto attendants relieve the load off staff by fielding incoming calls and routing them to the right destination. The automated attendant greets callers with a pre-recorded message, and options to be connected via the dialpad. It stops robocalls from getting any further, but also acts as a barrier to telemarketers who are often using an auto dialer.

Remove executive extensions from the company directory

A company telephone directory will route callers to the right person if they don’t know their direct extension. Telemarketers will often use the company directory to try and get through to different people until they can find a decision maker. With Telzio, you can remove certain users/extensions from being accessed by the company directory. This means that if a telemarketer searches for the CEO by name, her extension will not be searchable.

Request more information about the Spam Filter from Telzio.